Penicillin Allergy Testing

Katherine Tsai, MD

By: Katherine Tsai, MD

How many friends or family members do you know who have a penicillin allergy? Are you aware of the risks of having a penicillin allergy? All patients who have a history of penicillin allergy require allergy testing to confirm their diagnosis so that they do not unnecessarily avoid penicillin antibiotics.

Penicillin allergy downside

If a patient is truly allergic to penicillin, then it is not safe to take penicillin antibiotics. However, avoiding penicillin when a patient is not allergic is not ideal either.  Taking alternative antibiotics to penicillin will result in poorer outcomes for patients who will have inadequately treated infections. These patients may be treated with weaker, ineffective antibiotics or much stronger antibiotics which may not be first line treatments for their infections.

Penicillin allergy

Penicillin allergy – shot or pill

In the past, penicillin hypersensitivity was more common due to less pure formulations of penicillin. The method of delivery of penicillin also impacts its allergenic potential. Intravenous or intramuscular penicillin (through a needle either via IV or vaccination), which was more popular in the past, has a higher association with the development of anaphylaxis to penicillin. Today, oral amoxicillin or penicillin (pill form) is more frequently utilized and less likely to cause allergic hypersensitivity than injections.

Penicillin allergy truths

Since most patients who carry a diagnosis of penicillin allergy can actually tolerate penicillin, we recommend testing to improve patient outcomes. Evaluation of penicillin allergy can be performed at Colorado Allergy and Asthma Centers with skin testing followed by direct oral challenges after negative testing. Testing can be performed in children and adults that have withheld antihistamines. By testing patients and removing the label of penicillin allergy, we can promote proper antibiotic stewardship and patient wellness. Make an appointment today!